Thermally conductive silicone composition and production method therefor

Abstract

A thermally conductive silicone composition comprising(A) a crosslinked silicone gel,(B) a silicone oil containing neither an aliphatic unsaturated bond nor an SiH group,(C) a thermally conductive filler having an average particle diameter of 0.01-100 μm, the amount of which is 10-2,000 parts by mass per 100 parts by mass of the sum of the (A) and (B) components, and(D) gallium or a gallium alloy having a melting point of −20 to 100° C., the amount of which is 1,000-10,000 parts by mass per 100 parts by mass of the sum of the (A) and (B) components.The thermally conductive silicone composition has a high thermal conductivity and is excellent in terms of applicability and dislocation resistance.

1 . A heat conductive silicone composition comprising
 (A) a crosslinked silicone gel,   (B) a silicone oil containing neither aliphatic unsaturated bonds nor SiH groups,   (C) a heat conductive filler having an average particle size of 0.01 to 100 μm in an amount of 10 to 2,000 parts by weight per 100 parts by weight of components (A) and (B) combined, and   (D) gallium or a gallium alloy having a melting point of −20° C. to 100° C. in an amount of 1,000 to 10,000 parts by weight per 100 parts by weight of components (A) and (B) combined.   
     
     
         2 . The heat conductive silicone composition of  claim 1 , further comprising (E) a volatile solvent in an amount of 1 to 500 parts by weight per 100 parts by weight of components (A) and (B) combined. 
     
     
         3 . The heat conductive silicone composition of  claim 1  wherein component (B) contains (B-1) a silicone oil in the form of a one end hydrolyzable organopolysiloxane having the general formula (1): 
       
         
           
           
               
               
           
         
       
       wherein R 1  is each independently a C 1 -C 6  alkyl group, R 2  is at least one group selected from C 1 -C 18  aliphatic unsaturation-free, unsubstituted or substituted monovalent hydrocarbon groups, and a is an integer of 5 to 120, and component (B) is blended in an amount of 10 to 90% by weight based on the total weight of components (A) and (B). 
     
     
         4 . The heat conductive silicone composition of  claim 1  wherein component (A) is the addition reaction product of component (F) with component (G) in the presence of component (H), defined below,
 (F) an organopolysiloxane containing at least one silicon-bonded alkenyl group per molecule, represented by the average compositional formula (2):
   R 3   b R 4   c SiO (4−b-c)/2    (2)
 
 
 
       wherein R 3  is an alkenyl group, R 4  is an aliphatic unsaturation-free, unsubstituted or substituted monovalent hydrocarbon group, b is a number of 0.0001 to 0.2, c is a number of 1.7 to 2.2, and b+c is a number of 1.9 to 2.4,
 (G) an organohydrogenpolysiloxane containing at least 4 silicon-bonded hydrogen atoms at non-terminal positions of the molecular chain per molecule, and meeting the formula (3): 
 
       
         
           
             
               
                 
                   
                     
                       0. 
                       1 
                     
                     < 
                     
                       α 
                       / 
                       β 
                     
                   
                 
                 
                   
                     ( 
                     3 
                     ) 
                   
                 
               
             
           
         
       
       wherein α is the number of silicon-bonded hydrogen atoms at non-terminal positions of the molecular chain and β is the total number of silicon atoms in component (G),
 (H) a platinum base catalyst. 
 
     
     
         5 . The heat conductive silicone composition of  claim 1  wherein component (B) further contains (B-2) a non-functional liquid silicone oil having a kinematic viscosity of 10 to 500,000 mm 2 /s at 25° C., in an amount of 10 to 70% by weight of component (B). 
     
     
         6 . The heat conductive silicone composition of  claim 1  wherein component (E) is an isoparaffin base solvent having a boiling point of 80 to 360° C. 
     
     
         7 . A method of preparing the heat conductive silicone composition of  claim 1 , comprising the step of mixing components (B), (C) and (D). 
     
     
         8 . A method of preparing the heat conductive silicone composition of  claim 4 , comprising the steps of mixing components (F), (G) and (H) with components (B), (C) and (D), and heating the mixture to induce addition reaction of component (F) with component (G).